#include<stdio.h>
#include<math.h>
double  f(double x,int a,int b,int c)
{
    return a*pow(x,5)+x*x*b+c;
}
double fpro(double x,int a,int b,int c)
{
    return 5*a*pow(x,4)+2*x*b;
}
int main()
{
    int a,b,c;
    scanf("%d %d %d",&a,&b,&c);
    double x1=1.0;
    double x2=x1-f(x1,a,b,c)/fpro(x1,a,b,c);
    while(fabs(x2-x1)>=1e-5)
       {x1=x2;
        x2=x1-f(x1,a,b,c)/fpro(x1,a,b,c);
       }

    printf("%.2f",x2);
    return 0;
}